Welcome to the University of Texas Skywatchers' Report for May 13th through the 19th.

The moon is at first quarter on Sunday the 19th.

As the moon emerges in the evening skies after passing through the new phase on the 12th, it will join the impressive planetary line-up that skywatchers have been observing for the past couple of weeks. Just the barest hint of a crescent moon will appear next to Mercury on the 13th, very low in the west after sundown. On the 14th a larger crescent moon will move up along side a brilliant Venus, which always creates a photogenic display. On the 15th, the moon will be between the two brightest planets in the gathering - Venus and Jupiter. On the 16th, the moon will appear above the Jupiter, much higher in the west.

This grouping of the five naked eye planets is one of about 40 such conjunctions that have occurred over the past 4000 years, with the earliest recorded observations dating back about 3500 years. The next time these five planets will get together in a similar way will be in September 2040.

When you look at the slim crescent moon early this week, you may see the fainter part of the moon that is not receiving direct illumination from the sun. Instead, this part of the moon is showing something known as Earthshine, which light reflecting off the earth and illuminating the night side of the moon. Although this phenomena is beautiful, it can also be scientifically useful in measuring the Earth's reflectivity of sunlight, known as albedo and to do spectroscopic measurements of the Earth's atmosphere. This data is useful in many fields, ranging from Earth climate study to testing technologies that may help us detect other earthlike planets around other stars in our galaxy.

Public viewing on campus telescopes is currently on break between semesters. Summer viewing will resume in June. Please call this recording to check times before planning a visit to the telescopes.

Thank you for calling the University of Texas Skywatchers' report.

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